Non-caking alkyl aryl sulfonate detergent compositions



United States Patent NON-CAKING ALKYL ARYL SULFONATE DETERGENT COMPOSITIGNS Allen H. Lewis and Richard D. Stayner, Berkeley, Calif.,

assignors to California Research Corporation, San Francisco, Calif., a corporation of Delaware No Drawing. Application September 14, 1951,

Serial'No. 246,705

8 Claims. (Cl. 252-438) The present invention relates to improvements in particulate solid detergent compositions. More particularly, it relates to reduction and suppression of caking tendencies of particulate solid detergent compositions which contain as their active detergent ingredient sodium salts of alkyl benzene sulfonic acids having from 9 to 18 carbon atoms in the alkyl chain.

The larger proportion of commercial detergent compositions which owe their detergency to the presence of anionic organic sulfates and sulfonates are distributed on the market in the solid form, either as beads, flakes, chips, scales or granules, packed into containers such as metal drums, glass jars, wooden boxes or cartons. Many of these commercially available particulate solid. detergent compositions when stored in containers, and particularly when stored in cartons and wooden boxes, undergo considerable caking and lose thereby their free-flowing characteristics. This caking is particularly pronounced during storage in warm, humid climates, and is observed to occur even though the particulate detergent material is tightly covered or sealed in the container.

The occurrence of caking has been ascribed to a number of factors: It has been said that it is occasioned by the presence of the residual moisture in the dried detergent particles; on the other hand, many of those skilled in the art believe that caking results from the penetration of the atmospheric moisture into the container, even though it may appear to be perfectly well-sealed; again,

theories were propounded relating the phenomenon of caking to the particular physical structure or chemical nature of the detergent particles. Whatever be its true cause or causes, the occurrence of caking is highly undesirable and annoying. It interferes with. the free flow of the particulate detergent material from the package; on shaking the opened package to disintegrate or crumble the lumps of caked material, irritating dust rises into the air; and, in addition,v the remaining lumps are slow to dissolve inv the Wash Water.

Among the various anionic detergents, those represented by water-soluble sodium salts of monoalkyl benzene sulfonic acids in which the alkyl chain contains from 9 to 18 carbon atoms, and designated in the art under the name of alkyl benzene sulfonates are known to be eminently suitable for various industrial applications and, particularly, for household uses. However, even though these sulfonates are considered to be among the: most satisfactory and etficient detergents of the trade, they cake when exposed to warm and humid climatic conditions. This tendency to cake is responsible for the difiiculties encountered heretofore in marketing these compositions in the Southern States and, in general, in all areas characterized by humid, tropical or subtropical climates.

We have now found that by intimately admixing into the particulate detergent compositions containing in each 2,773,833 Patented Dec. 11, 1956 ice 100 parts by weight thereof from 10 to 'parts 'by weight of the aforementioned sodium salts of monoalkyl benzene snlfonic acids (sodium C9C1s monoalkyl benzene sulfonates), the remainder being essentially inorganic sodium salt builders, small amounts from 0.5 to 10.0%, and preferably from 1.0 to 5.0% by weight, based on the entire composition, of a sulfonate material from the group consisting of sodium benzene monosulfonate and sodium toluene monosulfonate, the extent of caking is very markedly reduced, and frequently caking is almost completely eliminated.

This finding is particularly remarkable and unexpected in view of the fact that the addition of like small amounts from about 0.5 to about 10.0% by weight of. other low molecular weight sodium aryl sulfonates, for instance, sodium meta-xylene monosulfonate, sodium tit-naphthalene monosulfonate, did not decrease but, on the contrary, increased the extent of caking in detergent compositions containing sodium C9C1s monoalkyl benzene. sulfonates.

The active sodium- C9'C1s alkyl benzene sulfonate ingredient of the detergent composition which can be improved or stabilized against caking, in accordance with our invention, may be produced in different ways. A particularly efficient detergent is prepared by alkylating benzene with a long-chain olefin or'an olefin polymer containing from 9 to 18 carbon atoms, e. g.,. C9-Cl8 polypropylene, in the presence of a suitable catalyst. The resulting C9-C13 alkylbenzene product, and preferably that fraction thereof which contains from 12 to 15 carbon atoms in the alkyl chain, is then subjected to. sulfonation with the aid of a suitable sulfonating agent suchas concentrated sulfuric acid, oleum, or S03. Upon completion of the sulfonation reaction, the unreacted sulfuric acid can be separated from thesulfonic acid by settling and decantation. Thereafter, the recovered alkyl benzene sulfonic acids are converted to sodium salts, by neutralization with an aqueous solution of caustic or-sodiurn carbonate. The prevailing practice is to leave all or a part of the unreactedsulfuric acid admixed with the alkyl benzene sulfonic acids and to neutralize them together to form an aqueous dispersion or slurry of the corresponding organic sodium alkyl benzene sulfonate and sodium sulfate.

Another procedure for the preparation of detergent sodium monoalkyl benzene sulfonates, which can be improved or stabilized against caking in accordance with additional sodium sulfate and/or other inorganic sodium salts, e. g., sodium silicate, and particularly phosphates such as tetra-sodium pyrophosphate or sodium tripolyphosphate, as well as sodium carboxymethyl cellulose, may be added as a suitable builder to the neutralized sulfonate slurry prior to drying the same in accordance with the particular specifications for the ultimately de sired detergent composition. The slurry thus built is then converted to the desired particulate solid form and size by an appropriate drying technique such as spray-drying or drum-drying.

We have observed that the presence of the aforemen- The.

tioned inorganic sodium sulfate and phosphate builders in the detergent compositions in the amounts up to about 89 parts by weight in each 100 parts thereof does not markedly interfere with the anti-caking effect of the additives of our invention, so long as the active sodium alkyl benzene sulfonate ingredient of a detergent composition is present therein in an amount ranging from about to about 95 parts by weight, and preferably from about toabout 60parts by weight, in which case the inorganic builder content of each 100 parts of the composition may range from about 80 to about 40 parts by weight.

, As mentioned hereinbefore, the effective additive for the prevention or reduction of caking in sodium alkyl benzene sulfonate detergents in accordance with the invention is selected from the group consisting of sodium benzene monosulfonate and sodium toluene monosulfonate. The recommended operative amounts of this caking preventive range from 0.5 to 10.0% and preferably from 1.0 to 5.0% by weight, based on the entire detergent composition including the active detergent ingredient and the inert builder or builders. By adding either one of the aforementionedtwo sulfonates in the amounts comprised in the aforementioned range from 0.5 to 10.0% by weight, the caking of the detergent composition can be makedly reduced and in most instances is substantially avoided. As will be seen from the description which follows, the-degree of improvement obtained for each particular composition may be varied somewhat depending on the exact amount of the caking preventive employed.

Different techniques may be employed to incorporate the caking preventive into the alkyl benzene sulfonate detergent compositions. Each one of these techniques aims at securing a uniform composition in the individual dry particles of the detergent composition, so that each individual particle consists of the detergent sulfonate, inorganic builder and caking-preventive sulfonate in substantially the same proportions. When dry sodium benzene sulfonate or dry sodium toluene sulfonate is added to a dry detergent composition in the small amounts of from 0.5 to 10.0% by weight, this uniformity of particle composition cannot be achieved and, as a consequence, the desired reduction in caking cannot be secured. In fact, upon adding to a drum-dried particulate detergent composition, each 100 parts of which contains 40 parts of active detergent sodium C12*C15 polypropylene benzene sulfonate and 60 parts of sodium sulfate builder, about 10% of dry powdered sodium benzene sulfonate, based on theweight of the detergent composition, and thoroughly mixing by mechanical means, the composition was observed to cake badly on storage, despite the presence of sodium benzene sulfonate.

A somewhat better intermixing of the caking preventive can be obtained by adding sodium benzene sulfonate or sodium toluene sulfonatefto the neutralized slurry of sodium C9C1a alkyl benzene sulfonate along with other additives and builders, whereupon the slurry will be dried and reduced to the desired particle form. However, this method may fall short of attaining the desired uniformity of the particles of detergent product if the degree of slurry agitation or the time of agitation is insuflicient. .Our. preferred procedure, which eliminates the possibility of a non-uniform distribution of caking preventive throughout the slurry and the consequent ineffectiveness of the caking preventives, consists in dissolving or dispersing benzene sulfonic or toluene sulfonic acid, or their sodium salts in the caustic soda solution to be used in neutraliz ing the mixture of alkylbenzene sulfonic acid and sulfuric acid.

Still another technique leading to the ultimate production of particles of uniform composition consists in adding benzene sulfonic acid or toluene sulfonic acid to the sulfonation reaction mixture of alkyl benzene sulfonic acid and unreacted sulfuric acid, whereupon the whole 4 is neutralized and dried. Also, one may add benzene sulfonic or toluene sulfonic acid to the mixture of C9C1a alkyl benzenes before subjecting this mixture to the sulfonation treatment. On neutralizing and drying the sulfonated mixture a product of uniform particle composition is obtained. Finally, one may incorporate the caking preventive by introducing benzene or toluene into the stock of C9-C18 monoalkyl benzenes about to be sulfonated. The mixture of the alkyl benzenes and benzene or toluene is then sulfonated and neutralized, yielding the desired mixture of sodium alkyl benzene sulfonate detergent and sodium benzene or toluene sulfonate in the proportions required for the efiective reduction of caking in accordance with the invention.

A large number of detergent compositions containing sodium alkyl benzene sulfonates with from 9 to' 18 carbon atoms in the alkyl chain have been tested for the reduction of their caking tendency afteradmixing various amounts of difierent low molecular weight sodium sulfonates, and subjecting samples of the compositions to tests in a humidity cabinet. The testing procedure employed was the following: After incorporating the low molecular weight sodium sulfonate into the detergent composition in accordance with one of the several methods indicated hereinbefore, the neutralized slurry was dried to yield a product of the desired particle size and shape. Weighed samples of the dried compositions, screened through a #16 sieve and collected on a #200 sieve, were placed in small untreated sealed cardboard.

boxes (l /2" x 2 /2" x 4"), and three samples of each detergent composition, together with three samples containing no low molecular weight sulfonate were placed in a completely randon manner in a humidity cabinet, exposed to a relative humidity of about at a temperature of about F. After the exposure period which lasted 7 days, the boxes with samples were reweighed, and the extent of caking was determined by cutting away an entire side of the cardboard box and carefully transferring the sample onto a #4 sieve /4" mesh) from a minimum height. The sieve was then gently swirled until all particles came. into contact with the screen. The material which did not pass through the screen by this treatment was considered to be caked and its weight vs. the weight of the original sample was designated as percent of material caked.

The following Table I contains the results of a number of tests carried out on samples of a representative alkylbenzene sulfonate detergentcomposition, namely, sodium polyproylene benzene sulfonate prepared in accordance with the procedure described in U. S. Patent No. 2,477,383, issued to A. H. Lewis on July 26, 1949, by polymerizing propylene to form a mixture of C12-Ci5 polypropylenes, alkylating benzene with these polypropylenes in the presence of a hydrofluoric acid catalyst,

n sulfonating, neutralizing with caustic soda solution and drying to small particles.

The data assembled in this table show the proportions of the active detergent, builder and caking preventive in each formulation in percent by weight, as wall as the method of'drying the formulation and the mode of incorporating'the caking preventive and finally the percent of material caked, based on the total detergent composition. To indicate the mode of incorporating the sodium benzenejmonosulfonate, sodium toluene sulfonate and other anti-caking additive, the following symbols are used in the table:

in which the low molecular weight aromatic sulfonic acid, such as benzene sulfonic, was added to the caustic i employed to neutralize the mixture of alkyl benzene sulcorporated in the neutralized slurry of sodium C9C1a alkyl benzene sulfonate and sodium sulfate.

sap-eases;

TABLE I Results of cakingtests on various detergent formulations Composition of Formulation Percent by Method of Method Percent Test No. weight of Percent Percent drying of incormaterials sodium Clr by Y by formulation porating caked C15 polyweight of Mime of additive weight of additive propylene sodium additive benzene sulfate sulionate 40 60. O Drum-dried-.- 65 40 59. 35 Sodium benzene sulfonate'. 0. 65 A 7 4O 1. 3 A 6 40 3. 2 A 10 40 6.1 A 2 40 8. 9 A 3 40 55. 7 Sodium ditertiary butyl benzene sulfonate 4. 3 A 72 40 53. 6 Sodium amyl naphthalene sulionate- 6. 4 A 100 40 57. 37 Sodium o-xylene sulfonate 2. 63 A 91 40 50. Sodium benzene sulfonate 10. 00 C l 40 59. 4 0. 6 A 40 58. 8 1.2 A 8 40 57 1 2. 9 A 20 40 54. 4 5. 6 A 10 40 51. 8 8. 2 A 1 40 57. 0 Sodium xii-xylene sulionate 3. 0 B 75 40 55. 0' do 5.0 B 100 40 52. 1 7. 9 A 71 40 57.0 Sodium p-xylene sulfonate 3. 0 B 70 40 55.0 5. O B 100 40 52. 7 Sodium alpha naphthalene sulionate 7. 3 A 96 40 60. 0 100 40 57. 0 Sodium benzene ultimate 3. 0 B 2 40 59. 0 1. 0 B 19 40 57.0 3.0 B 1 40 55.0 5.0 B 0 40 59. 0 1. 0 B 12 40 57. 0 3. 0 B 15 40 55.0 5. 0' B 1 The results presented in Table I clearly point out that the addition of low molecular weight monoaryl sulfonates from the group consisting of sodium benzene sulfonate and sodium toluene sulfonate effects a remarkable improvement in the quality of particulate alkyl benzene sulfonate detergent compositions by stabilizing them against caking on storage. This improvement brought about by the incorporation of caking preventives into the alkyl benzene sulfonate detergent compositions in relatively small amounts of the order of 1.0 to 5.0% by weight of the detergent composition is particularly unexpected in view of the lack of improvement generally observed upon incorporating many other low molecular weight aromatic sulfonates into such detergent compositions. In fact, frequently the caking is increased upon such an addition. Test runs Nos. 16, 17, 18, 19, and 21 of Table I, in which sodium meta-Xylene sulfonate, sodium para-xylene sulfonate and sodium iii-naphthalene sulfonate were used, illustrate this lack of improvement and the adverse effect of these additives on the stability of detergent compositions to caking.

Table 11 contains data relative to the efiect of addition of low molecular weight sulfonates in accordance with our invention to alkyl benzene sulfonate detergent formulations which in addition to sodium sulfate builder also contain sodium tripolyphosphate as a builder.

The samples containing the caking reventives and those without them were also compared with respect to detergency, wetting power and foaming power, and it was observed that the detergency, wetting power and foaming of the detergent compositions which contained either the sodium benzene sulfonate or sodium toluene sulfonate caking preventive in accordance with the invention were of the same order of magnitude as those of the compositions which contained no additive. Detergency measurements have been made by using hard-twisted white cotton strips soiled with a greasy soil (of oil, tallow and carbon black) in a Launderometer at 140 F., the detergent composition being employed in varying concentrations (0.1; 0.2; 0.3; 0.4%) in hard water (300 parts per million). Detergency (whiteness level) was rated with reference to an arbitrarily chosen standard called Soap Index, obtained with a 0.4% concentration of a well-known soap in hard water (300 parts per million) and assumed to be equal 100. Foam heights were determined by the Ross-Miles method described in Oil and Soap, vol. 18, p. 99 (1941). Wetting times in seconds were determined by the Canvas-Square Method, measuring the time required by a 1 inch square of 10 ounce #6 cotton-duck canvas to sink to the bottom when placed on the surface of 200 cc. of a solution of 0.25% of the sulfonate detergent com- TABLE II Results of coking tests 012- detergent formulations containing sodium sulfate and sodium tripolyphosphates as builders Composition of Formulation Sodium Method 012-015 Sodium Sodium Percent Method of of in- Percent Test polyprosulfate tripolyy drying corporatmaterial pylene in phosphate Additive to prevent caklng weight 111g cake benzene percent in percent of additive sulionate by by weight additive in percent weight by weight 36.8 *16. 5 42. 1 Drum-dried..- s4 36. 8 *14. 5 42. 1 Sodium benzene sulionate 1 36.8 16. 5 42. 1 100 36. 8 14. 5 42.1 Sodium benzene sulionate... 11 23. 5 21. 5 55.0 41 23. 5 19.5 55.0 Sodium benzene sulionate... 8

"Figures marked with an asterisk include 3.5% of sodium silicate and 1.1% of sodium carboxy methyl cellulose.

position in a 250 cc. beaker. Measurements were taken using both distilled and hard waters.

in the alkyl chain, the remainder of said detergent being essentially an inorganic sodium salt builder, and (b) Table HI contains representative test data on detergenfrom about 0.5% to about 10% by weight based on the cy, wetting power and foaming of detergent compositions entire composition of a sulfonate material selected from containing sodium benzene sulfonate and sodium toluene the group consisting of sodium benzene monosulfon-ate sulfonate caking preventives in accordance with the inand sodium toluene monosulfonate; said composition bevention. These data clearly show that the presence of ing in .the form of substantially non-calcing, dry particles caking preventives has no adverse effect on either of these of substantially uniform composition obtained by drying three significant characteristics of alkyl benzene sulfonate an aqueous dispersion containing said components (a) detergent compositions. and (b) of said composition.

TABLE III Test data on detergency, wetting and foaming of alkyl benzene sulfonate detergent compositions containing calving precentices Composition of Drum-Dried Formulation Wetting times Foam heights in mm. at in seconds at 0.2% concentration in Percent by Soap index 0.25% concentrahard water-percent weight Percent Percent by Percent at 0.2% tion inlard oil added Test sodium y weight by concentra- G g-C weight sodium Additive to prevent cakmg weight tion in pclysodium tri-polyof hard water propylene sulfate phosphate additive Distilled Hard benzene Water Water 0.0 0.1 0.2 1.0 sulfonate 60 59 22. 5 13 2 183 115 84 40 55 Sodium benzene sulionate 5 50 20. 5 13 7 184 139 122 85 40 57 d0 3 21. 6 14 2 182 160 150 107 40 57 Sodium toluene sulf nate-- 3 21. 3 15 7 178 156 140 112 36. 8 *1 6. 5 97 36. 8 14. 5 2 101 23. 8 21. 5 84 23 g 19, 5 Sodium benzene sulfonate 2 89 *Figures ma'ked with an asterisk include 3.5% of sodium silicate and 1.1% of sodium carboxymethyl cellulose.

Another surprising effect of the incorporation of sodium 2. The detergent composition of claim 1 wherein said benzene sulfonate or sodium toluene sulfonate caking sul-fona-te material is present in an amount equal to from preventives in sodium alkyl benzene sulfonate detergent about 1% to about 5% by weight based on the entire compositions in accordance with this invention is the composition. substantial improvement in the bulk color of dried de 3. The composition of claim 1 wherein said sulfonate tergent formulations. These formulations appear whiter material is sodium benzene monosulfonate. on visual observation. Tristimulus color measurements 4. 'The composition of claim 1 wherein said sulfonate likewise indicate that these formulations are substantially material issodium toluene monosulfonate, brighter. These latter determinations were made in ac- 5. The composition of claim 1 wherein said inorganic cordance with the procedure described in Handbook of sodium salt builder is sodium sulfate.

Colorimetry, by A. C. Hardy, published in 1936 by the 6. The composition of claim 1 wherein said inorganic Massachusetts Institute of Technology Press. In a typical Sodium salt builder is a sodium phosphate.

example of these colorimetric determinations, a sample 7. The composition of claim 1 wherein said detergent of the detergent formulation containing 40% by weight material contains in each 100 parts thereof from about 20 of sodium C12-C15 polypropylene benzene sulfonate, 57% t0 about 60 Parts y Weight a Sodium alt f a 1110110- by weight of sodium sulfate, and 3% by weight of so alkyl benzene sulfonic acid having from 12 to 15 carbon dium benzene sulfonate was found to have a 88.5% atoms i the alkyl Chain, Said alkyl Chain being defivfid brightness for a dominant wave length of 577 mo and 8% from a P py P saturation, while the same formulation without the cak- The method of preparing a s ti y a ing preventive displayed a degree of brightness equal to ing, Solid, Particulate detcrgent COmPOSifiOH which 6 79.5 at a dominant wave length of 587 m and 15% satuprises Providing a Slurry formed from t r and a li tio phase consisting essentially of a mixture of (a) a de- Considering the small proportions of sodium benzene tergent Containing in 621011 100 Parts thereof from 10 t sulfonate and sodium toluene sulfonate which efiectively 95 Parts by Weight of a Sodium Salt of a Inonoalkyl decrease the caking of the detergent composition, one can benzene sulfonic acid having from '9 to 18 carbon atoms readily appreciate that this and other previously menin the 'alkyl chain, wmaindel of said detergent being tioned advantages of our invention are secured with pracessentially all inorganic sodium salt builder, and from tically no increase in the manufacturing costs. about 05% 10 about 10% y Wfiight basfid r the 6 It should be understood that the foregoing description tire P of a Sulfonflte al selected from and experimental data are merely illustrative of the inthe group consisting of Sodium beHZBne sulfonatc vention and are not to be interpreted in limitation thereand 505111111 toluenfi monosu'lfonate, and Substantially f, except as d fi d i h annexed l i pletely removing water from said slurry to produce said W l i substantially non-caking detergent composition.

1. A substantially non-caking, solid, particulate detergent composition consisting essentially of a mixture of (a) a detergent material containing in each 100 parts thereof from 10 to 95 parts by weight of a sodium salt of a monoalkyl 2,477,383 benzene sulfonic acid having from 9 to 18 carbon atoms 2,615,847

References Cited in the file of this patent UNITED STATES PATENTS Lewis July 26, 1949 Thompson Oct. 28, 1952 

1. A SUBSTANTIALLY NON-CAKING, SOILD, PARTICULATE DETERGENT COMPOSITION CONSISTING ESSENTIALLY OF A MIXTURE OF (A) A DETERGENT MATERIAL CONTAINING IN EACH 100 PARTS THEREOF FROM 10 TO 95 PARTS BY WEIGHT OF A SODIUM SALT OF A MONOALKYL BENZENE SULFONIC ACID HAVING FROM 9 TO 18 CARBON ATOMS IN THE ALKYL CHAIN, THE REMAINDER OF SAID DETERGENT BEING ESSENTIALLY AN INORGANIC SODIUM SALT BUILDER, AND (B) FROM ABOUT 0.5% TO ABOUT 10% BY WEIGHT BASED ON THE ENTIRE COMPOSITION OF A SULFONATE MATERIAL SELECTED FROM THE GROUP CONSISTING OF SODIUM BENZENE MONOSULFONATE AND SODIUM TOLUENE MONOSULFONATE; SAID COMPOSITION BEING IN THE FORM OF SUBSTANTIALLY NON-CAKING, DRY PARTICLES OF SUBSTANTIALLY UNIFORM COMPOSITION OBTAINED BY DRYING AN AQUEOUS DISPERSION CONTAINING SAID COMPONENTS (A) AND (B) OF SAID COMPOSITION. 